Process-for the preparation of mono-



United States PROCESSFOR THE PREPARATION OF MONO- TERTIARY BUT -p-H-YDROXY ANISOLE George F. Rodgers, Kingsport, Tenn., assignor to Eastman Kodak Company,,Rocl1ester, N.v Y., a corporationof New Jersey No Drawing. Application March 12, 1952, Serial No. 276,220

1 Claim. (Cl. 2606'13) Monotertiary butyl 4-methoxyphenol is a valuableanti-oxidant for edible products. It can be etherified to form diethers of monotertiar-y butylhydroquinone which possess strong and charapteristic aromas, such as torender them of value in the preparation and blending of perfumes and commercial odorants. Of special interest has been an earthy, musty. character similar to that of raw potatoes and. Whichcompound has a low evaporation. rate and a.

correspondingly high life expectancy asan odorant. Moreover, these diethers have good compatibility with other compounds employed in the; preparation of odorants.

As. regards. the prior art relating to the preparation of monotertiary butyl-4-methoxyphenol, there is no description of the process of this invention although processes are. disclosed whereby dialkylated: phenols may be employedto alkylate phenols whereby the dialkylated phenols are, partially dealkylated to form monoalkylated derivatives. Thus, diamyl phenol can be reacted with phenol at 170 C. in the presence of sulfuric acid to form monoamyl phenol. The prior art does not disclose that solvents such as benzene can be advantageously employed in this type of reaction, although it is known that polyliydric phenols can be alkylated with olefins in solution in benzene. The prior art does, not suggest that boron trifluoride or any derivatives thereof can be advantageously employed as a catalyst in processes such as that of this invention.

I have discovered an improved process for partially matic hydrocarbon solvent employing as the catalyst boron tn'fluoride or certain of its derivatives.

It is an object of my invention to provide an improved process for converting dialkylated ethers of hydroquinone into the corresponding monoalkylated ethers of hydro- It is a further object to provide an especially effective catalyst for employment in such a process. More particularly, an object of my invention is the conversion by such a process of 2,5-ditertiary 'butyl-4-methoxyphenol into a mixture of Z-tertiary butyl-4-methoxyphenol and 3-tertiary butyl-4-methoxyphenol. Additional objects will become apparent hereinafter.

According to my invention a process is provided for preparing a mixture of 2- and 3-is omers of tertiary butyl- 4-methoxy phenol, hereinafter :referred to as mixed isomers thereof, which comprises reacting 2,5-ditertiary butyl-4-methoxyphenol with 4-methoxy phenol in the presence of boron trifluoride or certain of its derivatives in solution in an aromatic hydrocarbon of the benzene Patented. Aug- 2 1956.

series at a temperature. of from. about .-1-0, C. to about C.

ethers, etc. can also. be employed.

Inv general, morev of the, catalyst is required for a longer; time at thelower end of the rangejof +10 to=1:20 C. If-

xylene.

The lower limit of solvent would seem to be that at which the reactants and reaction products are immiscible. By the employment as a solvent of required. Temperatures in the upper part of the range given result in more rapid reaction. As pointed out above, more catalyst is generally required over a longer period of time at the lower temperatures. However, one

The following example will serve to further illustrate my invention:

Example I.BF3 as catalyst 118 grams of 2,5-ditertiary butyl-4-methoxyphenol and 62 grams of 4-methoxyphenol were dissolved in 200 cc. of benzene and 4.0 grams of boron trifluoride was introduced at 25 C. The mixture was stirred for three hours the temperature employed is reduced somewhat. This is and then allowed to stand at room temperature, followillustrated by the following example: ing which the mixture was water-washed and the benzene Example of H2504 as Catalyst at was removed by distillation. Finally, the residual material was distilledat reduced'pressure. The distilled Materials employed in Examples 2 and 3 were mixed product weighed 168.7 grams and upon analysis was 111 the same Proportions and the same p f d t i h foll wi ployed except that the temperature was 30 and the 1 amount of catalyst was 15 cc. (27.8 grams) which is about 17'8% zs'dltemary bmy1'4'methoXyphen0l 31% based on the weight of the reactants employed. The

21.3% hydroquinone monomethyl ether distilled product obtained had the following analysis: 44.8% 3-tert1ary butyl-4-methoxyphenol 2-tertiary butyl-4-methoxyphenol 26.7% 2,5-ditertiary butyl-4-methoxyphenol 18.3% hydroquinone monomethyl ether Higher temperatures and continued stirring for ex- 413% 346mm butyl 4 methoxyphenol tended periods of time can be employed to effect more 133% LteItiaI-y butyl 4 methoxyphenol rapid reaction or the mixture can be allowed to stand at room temperature for extended periods of time, e. g., 65 E e though good y e s are obtamed when sulfunc hours as in Example 1, whereby continued stirring at ele- 301d lllgll concentratlofl 1s p y as f y f vated temperatures is unnecessaryto obtain good yields. better Welds can be Obtalned when boron trlfluorldsp Larger quantities of boron trifluoride can be employed to sfl'fployed at lower mp f j see Example It IS obtain more rapid reaction. Addition complexes of boron 20 9 that boron mfluonde 15 an excellent catalyst trifluoride with alcohols, ethers, acids, etc., can be em- Whlch can be mp y at Y temperatures and 111 ployed in place of boron trifluoride per se. lower concentrations to effect improved results as com The following examples illustrate for comparison the pared to the Fmployment of sulfur"; acid; Alzlothel' employment f lf i acid as the catalyst; vantage obtained by the use of boron trifluoride as the i a catalyst as in Example 1 can be lllustrated by consider- Example of HZSO4 as Catalyst at 40 ing the factthat one of the isomers of the product ob- 59 grams of 2,5-ditertiary butyl-4-methoxyphenol, 31 willed, y butyl-4'methoxyphsflol, is the most grams of 4-methoxypheno1, 200 f benzene d 1 potent isomer as a food antioxidant. The use of boron (about 2% by weight) f 104% H were i d d trifluoride in Example 1 results in a ratio of this isomer to stirred at 40 C. for four hours. After water-washing the 30 the much less Potent 150K161 of about r as t solvent was removed and the product was distilled at reratio of isomers when acid s p y is less duced pressure. The distilled product had the following than Example 2, 1s abollt 111 E p and analysis; only approaches the more desirable ratio of Example 1 66 8% 2 iditeniary.butYlAmwthoXYPhenol when the very high proportion of catalyst of Example 3 is employed, thereby resulting in a ratio of 0.32.

285% 4'meihoxyphenol What I claim as my invention and desire to secure by 3'tertlary butyl'4'methoxyphenol Letters Patent of the United States is: 02% z'tertlary butyl'4'metho7liy'phenol A process for preparing a mixture of about 0.36 pro By increasing the temperature without increasing the portion by weight of 2-tert. butyl-4-methoxyphenol for quantity of sulfuric acid catalyst, the following results can 40 a h proportion by Weight of 3-tert. buty1-4-methoxybe obtained: phenol which comprises reacting 1 mole of 2,5- ditert,

butyl-4-methoxy-phenol with 1 mole of 4-methoxy henol Example 3' 2% of H2504 as Catalyst at 60 dissolved in benzene at room temperature in the pgesence The quantities of materials in the procedure in Example of from 1 to 5% by weight of the reactantsof boron tri 2 were repeated exactly except that the temperature emfluoride. ployed was C. The distilled product obtained had the following analysis:

41.0% 2,5 -ditertiary butyl-4-methoxyphenol References Cited in the file of this patent UNITED STATES PATENTS 32.0% 4-methoxypheno1 2,189,805 Kyrid s Feb. 13, 1940 22.2% 3-tertiary butyl-4-methoxyphenol 2,553,538 Arnold May 1951 245 -1131 butyl 4-methoxyphenol Stevens et y 2,676,191 Hoat on et l A 20, 1954' The preceding example illustrates the efiectiveness of S a pr increasing the temperature insofar as increasing the yield OTHER REFERENCES obtained is concerned. The yield can be similarly in- 5 Niederl: Industrial & Engineering Chem, vol. 30, No. creased by increasing the amount of catalyst even when 11, p. 1270 (November 1938). 7 

